Fluid resistant silicone compositions for sealing magnesium alloy components

ABSTRACT

Silicone compositions are disclosed which exhibit excellent adherence to magnesium-based substrates such as magnesium alloys and which exhibit excellent resistance to organic solvents. These compositions include at least one polymerizable silicone component, at least one amino-containing silane adhesion promoter which enhances adhesion of the composition to magnesium-based substrates, and at least one viscosity modifier, which enhances the resistance of the compositions to organic solvents. Methods of making these compositions, articles of manufacture including these compositions, and a method for providing enhanced adhesion to magnesium-based substrates using these compositions are also disclosed.

This application claims benefit of provisional application No.60/166,011, filed Nov. 17 1999.

FIELD OF THE INVENTION

The present invention relates generally to compositions for sealing andadhering magnesium-based substrates. More particularly, the presentinvention relates to compositions which demonstrate excellent resistanceto fluid solvents, particularly automotive fluids, while maintainingexcellent adherence to magnesium-based substrates.

BACKGROUND OF RELATED TECHNOLOGY

Room temperature vulcanizable (RTV) silicones posses an interestingcombination of properties that make them very desirable for a largenumber of applications. These properties include a viscosity range thatallows for use as flowable liquids or soft pastes, excellent thermalstability characteristics of high-consistency silicone rubber, goodadhesion to many surfaces without requiring pressure, and curing withoutthe need for heating, as their name implies. However, RTV silicones havenot been used for sealing and bonding magnesium-based substrates, suchas magnesium alloy substrates.

It is known to add viscosity-modifying filler materials to RTV siliconesto improve their resistance to fluid solvents. For example, the additionof certain grades of metal oxides to silicone elastomers is known toresult in silicone rubber compositions having a certain degree of oilresistance. European Patent Publication No. 572 148, assigned to GeneralElectric Company, discloses the incorporation of mixed metal oxides intoheat cured silicone elastomeric compositions containing MQ resins(M=R₃SiO_(1/2) monofunctional groups; Q=SiO₂ quadri- functional groups).In the '148 publication, such compositions are formed into enginegaskets which are reported to display a certain degree of oilresistance.

It is further known to add silane compounds to silicone elastomers toimprove the adhesive properties of RTV silicone compositions. Forexample, U.S. Pat. No. 5,569,750 to Knepper et al. discloses a siliconerubber composition including an aminohydrocarbyl-substitutedketoximinosilane which reportedly possesses improved adhesiveproperties.

Silicone elastomers are commonly used as adhesives and sealants inautomotive applications. For instance, U.S. Pat. Nos. 4,847,396 and4,735,979, both assigned to Loctite Corporation, disclose RTV siliconecompositions as automotive sealants. These patents disclose the use ofadhesion promoters in silicone compositions to improve the adhesivestrength of the silicone compositions to ferrous and aluminumsubstrates, even when these substrates have motor oil coated on theirsurfaces. Further, U.S. Pat. No. 5,434,214, also assigned to LoctiteCorporation, discloses hydrosilation cured silicone formulations whichcure at room temperature and, after a subsequent heat cure cycle,provide good primerless adhesion to aluminum and titanium substrates.

Magnesium alloys, typically alloys which include magnesium, aluminumand, to a lesser degree, zinc and manganese, have traditionally beenused in aeronautic applications. They are characterized as being lightin weight, offering high strength, being easily molded, having theability to withstand high tolerances, and having the ability towithstand high temperatures. As a result of these properties, magnesiumalloys are finding increased utility in other areas, such as automotiveapplications.

Magnesium alloys have traditionally been joined by riveting or welding.It is desirable, however, to bond and seal magnesium alloys usingadhesives, as adhesive bonding and sealing offers advantages in weightsaving, fatigue strength, and corrosion resistance. Attempts at suchbonding and sealing, however, have proven generally commerciallyunacceptable for many applications, particularly automotive applicationswhere the adhesives are exposed to automotive fluids, such as engineoils and coolants, at temperatures observed during operation of anautomobile engine. These fluids tend to degrade the adhesives, therebydestroying their ability to seal and bond the substrates. Further,oxidation on the surface of magnesium alloys results in the formation ofa layer of magnesium oxide which prevents bonding of adhesive materialsto the underlying magnesium alloy.

Therefore, there exists a need for an elastomeric composition whichexhibits improved adherence to magnesium-based substrates such asmagnesium alloys, maintains structural integrity upon exposure to fluidsolvents, and exhibits flexibility when subjected to thermal andmechanical stresses. The current invention is directed towards meetingthese and other needs.

SUMMARY OF THE INVENTION

The present invention is directed to compositions which are suitable foruse as sealants and adhesives on magnesium-based substrates such asmagnesium alloy substrates. Particularly, the present invention isdirected to a silicone composition, the reaction products of whichdemonstrate improved adhesion to magnesium-based substrates, whichincludes at least one polymerizable silicone component, at least oneamino-containing silane adhesion promoter, and at least one filler.These compositions demonstrate excellent resistance to fluids, such asautomotive fluids, while maintaining their enhanced adherence tomagnesium-based substrates. Additionally, these compositions maintaintheir structural integrity when subjected to thermal and mechanicalstresses. Desirably, the compositions include one or more polymerizablesilicone polymers, such as RTV silicones, at least one amino-containingsilane compound which serves as a magnesium alloy adhesion promoter, andat least one filler which serves to provide fluid resistance to thecompositions. The present compositions can be used to seal interfacesbetween magnesium-based substrates, bond magnesium-based substratestogether, and bond magnesium-based substrates to non-magnesium-basedsubstrates. The present invention is also directed to a method forproviding enhanced adhesion to magnesium-based substrates by disposing acomposition of the present invention between two substrates and thencuring the composition. Additionally, the present invention is directedto an article of manufacture including a composition of the presentinvention.

Compositions of the present invention can be dispensed onmagnesium-based substrates in a liquid phase and allowed to cure at roomtemperature or can be cured prior to application to form automotivesealant devices, such as gaskets and o-rings. Methods of making thesecompositions and their use are also disclosed.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is directed to compositions which are curable toan elastomeric state and which exhibit improved adherence tomagnesium-based substrates such as magnesium alloys and enhancedresistance to fluids, such as those commonly used in and aroundautomotive engines. Compositions of the present invention includepolymerizable silicone compounds, such as reactive polysiloxanes, atleast one amino-containing silane compounds, and at least one filler.

Any conventional polysiloxane may be used in compositions of the presentinvention and may be present in any amount, provided the resultingcompositions effectively bond to magnesium-based substrates, formeffective seals when cured, and are rendered substantially insoluble orresistant to automotive fluid solvents. For example, room temperaturecuring, actinic radiation curing, heat curing or silicones which cure bymore than one of these mechanisms may be used. Desirably, thepolysiloxane is an RTV compound. RTV compounds are typicallylow-consistency silicone elastomers that can be easily extruded from atube or other dispenser and subsequently cured. Silicones which cure atroom temperature may exist in one-part systems or in two-part systems.

In a one-part system, the silicones are typically organosiloxanecompounds which may include hydrolyzable groups on their ends. They arestored in a noncrosslinked state in a moisture-impermeable containeruntil they are to be used. When they are removed from the container andexposed to moisture, the hydrolyzable groups react with the moisture ina condensation reaction, resulting in crosslinking of the polymer. Anexample of an RTV organopolysiloxane is a hydroxy-terminateddiorganopolysiloxane represented by the formula:

wherein m is from about 50 to about 2000, desirably from about 500 toabout 800, R is independently an unsubstituted or substituted monovalenthydrocarbon group exemplified by alkyl groups, such as methyl, ethyl,propyl and butyl groups; cycloalkyl groups, such as a cyclohexyl group;alkenyl groups, such as vinyl and allyl groups; and aryl groups, such asphenyl and tolyl groups; as well as those substituted groups obtained byreplacing a part or all of the hydrogen atoms in the above-referencedhydrocarbon groups with halogen atoms, cyano groups and the like.

Desirably, the polysiloxane used in the present invention is ahydroxy-terminated poly(dimethylsiloxane). This polysiloxane may also bea single hydroxy-terminated poly(dimethylsiloxane) or may be acombination of hydroxy-terminated poly(dimethylsiloxanes) which are ofdifferent viscosities. For example, they may have viscosities of from2000 cps to 10,000 cps, correlating to a molecular weight range ofapproximately 36,000 to 60,000. Such hydroxy-terminatedpoly(dimethylsiloxane) compounds are available commercially from UnionCarbide, identified by proprietary designations Y-7839 and Y-7869, andfrom Mobay, identified by proprietary designation Baylisone E-2.

RTV silicone compositions have long been used in automotive and otherapplications and many variations thereof are known. By way of example,RTV silicones have been formulated as automotive enginecured-after-assembly gasketing materials where high temperatureaggressive fluids, such as engine coolant and motor oil, create aparticularly hostile environment. Examples of silicones formulated forsuch automotive gasketing applications are described in U.S. Pat. Nos.4,673,750 (Beers et al.), 4,735,979 (Beers et al.), 4,847,396 (Beers etal.), and 5,346,940 (Brassard et al.), all expressly incorporated byreference herein.

Useful heat curable siloxanes that may be used in the present inventioninclude, but are not limited to, linear polyorganosiloxanes, monomericsiloxanes, polydimethylsiloxane chains having SiH functionality locatedat either the ends or the middle of the chains, cyclic siloxanes andcombinations thereof. Particularly useful heat curable silicones includepolysiloxanes in combination with vinyl-terminated low molecular weightpolysiloxanes. More particularly, dimethyl vinyl-terminatedpolydimethylsiloxane (10,000 MW vinyl fluid) and vinyl-terminatedpolydimethylsiloxane (62,000 MW vinyl fluid) may be used as a heatcurable polymer in the present invention.

Heat curable polyorganosiloxanes having olefinic unsaturation shouldcontain at least one reactive functional group, and desirably tworeactive functional groups. More than two reactive functional groups arealso contemplated. The number and type of functional group or groupspresent can be varied according to the desired properties of the finalsilicone composition. The organic groups of the polyorganosiloxane aremonovalent hydrocarbon radicals and preferably the organo groups areselected from alkyl radicals, such as methyl, ethyl, propyl, etc.;alkenyl radicals such as vinyl, allyl, etc.; cycloalkyl radicals such ascyclohexyl, cycloheptyl, and; mononuclear aryl radicals such as phenyl,ethylphenyl; and haloalkyl such as 3, 3, 3-trifluoropropyl.

Heat curable polyorganosiloxanes useful in the present invention arerepresented by the following general formula:

wherein n is an integer such that the viscosity is from about 25 cps toabout 2,500,000 cps at 25° C., such as when n is from 1 to 1,200 anddesirably from 10 to 1,000; R¹, R², R³ and R⁵ can be the same ordifferent and are substituted or unsubstituted hydrocarbon orhydrocarbonoxy radicals from C₁₋₂₀, provided that at least one of theseR groups, and desirably more than one, are selected from the reactivefunctional groups consisting of (meth)acrylate, carboxylate, maleate,cinnamate and combinations thereof, and provided that the reactivefunctional group is not directly bonded to a silicon atom, but separatedfrom the silicon atom by an intervening chemical moiety, such as an atomor chemical group. For example, when one or more of the aforementioned Rgroups (R¹, R², R³ and R⁵) is not one of the required reactivefunctional groups, they can be chosen from alkyl radicals such asmethyl, ethyl, propyl, butyl and pentyl; alkenyl radicals such as vinyland allyl; cycloalkyl radicals such as cyclohexyl and cycloheptyl; arylradicals such as phenyl, methylphenyl, ethylphenyl; arylalkyl radicalssuch as beta-phenylethyl; alkylaryl radicals; and hydrocarbonoxyradicals such as alkoxy, aryloxy, alkaryloxy, aryalkoxy, and desirablymethoxy, ethoxy or hydroxy, and the like. Any of the foregoing radicalsmay have some or all of the hydrogen atoms replaced, for example, by ahalogen such as fluorine or chlorine. One or more of the aforementionedR groups can also be hydrogen, provided the required reactive functionalgroup is present as indicated and the presence of the hydrogen does notdeleteriously interfere with the ability of the polyorganosiloxane toperform in the present invention. R³ in the above formula desirably is avinyl group or a dimethyl vinyl group.

Radiation curable silicones, particularly those curable by ultravioletlight (UV) and electron beam (EB), may also be used in the presentinvention. Organopolysiloxane polymers are rendered radiation hardenableby functionalizing them with radiation susceptible groups. The threemost common groups used to convert silicones as radiation curable aremercapto-olefins, epoxies, and acrylics. For instance, acrylics andmercapto-olefins crosslink by free radicals and, therefore, can becrosslinked in the presence of suitable photoinitiators. One example ofa UV curable silicone composition useful in the present invention isdescribed in U.S. Pat. No. 5,300,608 (Chu), the disclosure of which isexpressly incorporated herein by reference. The photocurable siliconecomposition is described therein to include alkoxy-terminatedorganopolysiloxanes represented by the formula:

wherein R¹, R², R³ and R⁴ may be identical or different and aremonovalent hydrocarbon radicals having up to 10 carbon atoms (C₁₋₁₀), orhalo or cyano substituted hydrocarbon radicals; R³ may also be amonovalent heterohydrocarbon radical having up to 10 carbon atoms(C₁₋₁₀), wherein the heteroatoms are selected from the group consistingof haloatoms, O, N; R⁵ is alkyl (C₁-C₁₀), preferably methyl, ethyl orisopropyl; R⁵ may also be a CH₂CH₂OCH₃; n is an integer; a is 0, 1 or 2;b is 0, 1 or 2; and a+b is 0, 1 or 2. In a particularly desirableembodiment, R³ is a methacryloxypropyl group, R⁴ and R⁵ are methylgroups, and R¹ and R² are methyl groups. The alkoxy-terminatedorganopolysiloxanes can be prepared as described in the '608 patent.

It is also known to cure polymerizable silicone compounds by more thanone curing method. For example, U.S. Pat. No. 5,212,211 (Welch II etal.), expressly incorporated by reference herein, discloses a siliconecompound which is curable by more than one method of curing, such asheat curing, moisture curing, or curing with ultraviolet light. U.S.Pat. No. 5,516,812 (Chu et al.), expressly incorporated by referenceherein, discloses a silicone composition which is both UV and moisturecured. Additionally, European Patent 539 234 discloses a composition forliquid gasketing which has both an UV curing property and amoisture-curing property and Japanese Patent Application No. 92143102 toTokyo Three Bond Co., Ltd. discloses compositions which are bothmoisture curable and UV curable.

While specific examples of siloxane polymers which may be used in thepresent invention have been illustrated, these examples are in no waymeant to be limiting. It will be apparent to those skilled in the artthat numerous silicone polymers are suitable for use in compositions ofthe present invention, including those which are curable by more thanone means.

Compositions of the present invention also include one or moreamino-containing silane compounds which act as adhesion promoters. Theseamino-containing silane compounds are present in amounts of about 0.1percent by weight of the composition to about 5.0 percent by weight ofthe composition. Desirably, these compounds are present in amounts ofabout 0.74 percent by weight of the composition to about 1.4 percent byweight of the composition. Amino-containing silane compounds which areuseful in the present invention include, but are not limited to, silanecompounds containing amino-alkyl groups, such asgamma-ureidopropyltrimethoxy silane, 3-aminopropyl trimethoxysilane,N,N′-bis(3-trimethoxysilylpropyl)urea,gamma-aminopropyltrimethoxysilane,N-(2-aminoethyl)-3-aminopropyltriethoxysilane,N-(2-aminoethyl)-3-aminopropyltrimethoxysilane,trimethoxysilylpropyldiethylene triamine, tertiary alkyl carbamatesilane, and aminoethyl-3-aminopropyl-methyl-dimethylsilane. Otherdesirable amino-containing silane compounds include silane compoundscontaining amino-cycloaliphatic groups such as methyltris(cyclohexylamino)silane and silane compounds containingamino-aromatic groups such as methyl tris-(N-methylbenzamido)silane.

In addition to at least one or more amino-containing silane compound,one or more additional silane compounds may be present in thecomposition of the present invention. Generally, these additional silanecompounds serve as crosslinking agents. Examples of these additionalsilane compounds include, but are not limited to,methyltrimethoxysilane, vinyltrimethoxysilane, methyltriethoxysilane,vinyltriethoxysilane, methyltriacetoxysilane, vinyltriethoxysilane,methyltriacetoxysilane, methyl tris-(isopropenoxy)silane, enoxysilane,tetra (methyl ethyl ketoximino) silane/vinyl tris(methyl ethylketoximino) silane 1:1, vinyl tris(methyl ethyl ketoximino) silane,glycidoxpropyl trimethoxysilane, 3-glycidoxypropyltrimethoxy silane,gamma-mercaptopropyltrimethoxysilane,gamma-methacryloxypropyltrimethoxysilane, methyl tris-(methyl ethylketoximino)silane, vinyl tris-(methyl ethyl ketoximino)silane, methyltris-(methyl isobutyl ketoximino)silane, vinyl tris-(methyl isobutylketoximino)silane, tetrakis-(methyl ethyl ketoximino)silane,tetrakis-(methyl isobutyl ketoximino) silane, tetrakis-(methyl amylketoximino)silane, dimethyl bis-(methyl ethyl ketoximino)silane, methylvinyl bis-(methyl ethyl ketoximino)silane, methyl vinyl bis-(methylisobutyl ketoximino)silane, methyl vinyl bis-(methyl amylketoximino)silane, tetrafunctional alkoxy-ketoxime silane, andtetrafunctional alkoxy-ketoximino silane. For example, tetra (methylethyl ketoximino) silane/vinyl tris(methyl ethyl ketoximino) silane 1:1is desirably used in the present invention. Tetra (methyl ethylketoximino silane is represented by the following general formula:

Vinyl tris(methyl ethyl ketoximino) silane is represented by thefollowing formula:

It will be apparent to one skilled in the art that any combination ofone or more amino-containing silane compounds and one or more additionalsilane compounds be present in the composition of the present inventionso long as the composition exhibits the desired magnesium alloyadherence properties of the present invention.

The fillers used in the present invention provide fluid solventresistance to reaction products of the composition, i.e., the curedcomposition. In the present invention, this is particularly importantwhere the composition is used as a sealant or bonding agent for castmagnesium alloy substrates in automotive applications. Such substratestypically are in contact with automotive fluids, such as engine oils,transmission fluids, and coolants. The compositions of the present arenot degraded by these fluids, making them desirable for such automotiveuses.

Fillers which are used for imparting desired characteristics toelastomeric substances, and, consequently, which are suitable for use inthe present invention, are known to those skilled in the art. They areadded to compositions to impart desired properties to the composition.Such properties include heat stability, flame retardation, improvedhandling properties (e.g., elasticity), improved vulcanizationproperties, desired coloration, resistance to fungi, resistance tomildew, ability to absorb ultraviolet rays, and thermal and electricalconductivity. Such fillers include, without limitation, carbon black,aluminum flake (aluminum pigment powder in mineral oil), silane-treatedfumed silica, precipitated silica, stearate coated calcium carbonate,calcium carbonate, iron aluminum silicate, magnesium oxide, talc, groundquartz, clay, titanium dioxide, iron oxide, and various other metaloxides such as cerium, zinc, and barium oxides.

Having set forth examples of suitable compounds which may be present incompositions of the present invention, specific examples of compositionswhich were formulated and tested will now be set forth in detail below.

Base Composition A. Compound % (w/w) Hydroxy-terminatedpoly(dimethylsiloxane) mixture¹ 50.95 Carbon black 0.25 Hydrophobicfumed silica 2.00 Stearate coated calcium carbonate 10.00 Calciumcarbonate 25.00 Magnesium oxide 5.00 Tetra (methyl ethyl ketoximino)silane/ 1.5 vinyl tris (methyl ethyl ketoximino) silane 1:1 Vinyl tris(methyl ethyl ketoximino) silane 5.00 Hexafunctional silyl ethane 0.30100.00 ¹Combination of 12.00% w/w 2000 cps Hydroxy-terminatedpolydimethyl siloxanes and 38.95% w/w 6000 cps Hydroxy-terminatedpolydimethyl siloxanes.

A mixture of hydroxy-terminated polydimethyl siloxanes (12% w/w 2000 cpsand 38.95% w/w 6000 cps), carbon black, hydrophobic fumed silica,stearate coated calcium carbonate, calcium carbonate, and magnesiumoxide were combined and mixed at medium speed while heating to 210-220°F. The mixture was then mixed at high speed under a vacuum for 90minutes and cooled to 180+/−5° F. Once this temperature was reached, themixture was removed from the vacuum. The tetra (methyl ethyl ketoximino)silane/vinyl tris(methyl ethyl ketoximino) silane 1:1 and a first sampleof the vinyl tris(methyl ethyl ketoximino) silane was then added to themixture. This mixture was then mixed at medium speed for 15 minutes in anitrogen environment. After 15 minutes, a second sample of the vinyltris(methyl ethyl ketoximino) silane was added to the mixture. Themixture was then allowed to cool. The mixture was then mixed under avacuum until the temperature of the mixture was below 110° F. The vacuumand nitrogen were then removed and the hexafunctional silyl ethane wasthen added to the mixture. The mixture was mixed for 15 minutes under avacuum and allowed to cool. The composition was extruded at 90 psi at arate of 300 g/min. The resulting composition had the following physicalproperties: Hardness Shore A=48; Tensile Strength (psi)=252 psi; 100%Modulus (psi)=191; % Elongation=179.

Base Composition B. Compound % (w/w) Hydroxy-terminatedpoly(dimethylsiloxane) mixture¹ 50.00 Carbon black 0.20 Hydrophobicfumed silica 3.00 Stearate coated calcium carbonate 10.00 Calciumcarbonate 25.00 Magnesium oxide 5.00 Tetra (methyl ethyl ketoximino)silane/ 1.5 vinyl tris (methyl ethyl ketoximino) silane 1:1 Vinyl tris(methyl ethyl ketoximino) silane 5.00 Hexafunctional silyl ethane 0.30100.00 ¹Combination of 11.00% w/w 2000 cps hydroxy-terminatedpolydimethyl siloxanes and 39.005% w/w 6000 cps hydroxy-terminatedpolydimethyl siloxanes.

Various silane compounds were mixed with 100 g of Base Composition A toproduce the Inventive Compositions 1-7 shown in Table 1.

TABLE 1 Inventive Compositions 1-7. Compo- Amount % Silane sition SilaneAdded to Base Composition A (g) (w/w) 1 Glycidoxpropyl trimethoxysilane1.50 1.40 2 3-aminopropyl trimethoxysilane 1.50 1.40 3N,N′-bis(3-trimethoxy silylpropyl)urea 1.50 1.40 4 Tertiary alkylcarbamate silane 1.50 1.40 5 Vinyltriisopropoxy silane 1.50 1.40 62-diphenylphosphinoethyltriethoxy- 1.50 1.40 silane 7Trimethoxysilylpropyldiethylene- 1.50 1.40 triamine

Additionally, various silane compounds were mixed with 100 g of BaseComposition B to produce the Inventive Compositions 8-14 shown in Table2.

TABLE 2 Inventive Compositions 8-14. Compo- Amount % Silane sitionSilane Added to Base Composition B (g) (w/w)  8Trimethoxysilylpropyldiethylene- 1.00 0.90 triamine  9Trimethoxysilylpropyldiethylene- 0.75 0.74 triamine 10Aminoethyl-3-aminopropyl-methyl- 1.50 1.40 dimethylsilane 11Tris-[3-(trimethoxysilyl)propyl] 1.50 1.40 isocyanurate 12Aminoethyl-3-aminopropyl-methyl- 1.00 0.99 dimethoxylsilane 13Aminoethyl-3-aminopropyl-methyl- 0.50 0.50 dimethoxylsilane 14Gamma-ureidopropyltrimethoxy silane 0.75 0.74 andAminoethyl-3-aminopropyl-methyl- dimethylsilane

Composition 7 was chosen as a representative for measurement of thefollowing physical properties: Hardness Shore A=46; Tensile Strength(psi)=307; 100% Modulus (psi)=254; % Elongation=134.

Lap shear specimens were prepared for Base Composition A, which servedas a control, and for compositions 1-13 using magnesium and aluminumsubstrates. The magnesium and aluminum substrates were used in each lapshear test such that each specimen included a layer of magnesium alloy,the composition being tested, and a layer of aluminum. The specimens had½ inch overlap and 0.040 inch gap. The prepared samples were cured for 7days at room temperature and 50% relative humidity. The specimens werepulled at 0.5 inches/minute per American Standard Test Method (ASTM)DI1002. The results of these measurements are shown in Table 3.

TABLE 3 Lap Shear Measurement for Base Composition A and Compositions1-13. Compo- Shear Type of sition Strength (psi) Failure¹ Base A 64 100%AF @ Mg 1 89 75% AF @ Mg 2 123  33% CF @ Mg 3 73 100% AF @ Mg 4 75 100%AF @ Mg 5 74 100% AF @ Mg 6 61 66% AF @ Al 7 153  30% CF @ Mg 8 134  20%CF @ Mg 9 98 10% CF @ Mg 10  133  95% CF @ Mg 11  94 100% AF @ Mg 12 192  50-80% CF @ Mg 13 93 100% AF @ Mg ¹AF = Adhesive Failure CF =Cohesive Failure

As noted above, all but one of the inventive compositions exhibited asubstantial increase in tensile shear strength, with more than half ofthem demonstrating cohesive failure, as opposed to adhesive failure.Cohesive failure, or failure within the adhesive as opposed to at thebondline interface, indicates that the adhesion to the magnesiumsubstrate is stronger than the adhesive per se. Such failure isdesirable in the present invention as it indicates enhanced adherence tothe magnesium substrate. With Base Composition A, a relatively lowapplication of stress is needed to effect complete adhesive failure.Modification of Base Compositions A and B with the addition of variousamino-containing silanes, represented in Tables 1 and 2, necessitatesthe application of significantly greater stress to effectuate failure ofthe composition.

Certain lap shear specimens demonstrating excellent magnesium alloyadherence properties were subsequently subjected to individual immersionin an aqueous solution of 50% Honda® LC coolant and Honda® MTF gear oiland shear strengths were measured as above. The results of these testsare shown in Tables 4 and 5, respectively.

TABLE 4 Lap Shear Measurements for Compositions 7, 10, 12 and 13Subsequent to Immersion in an Aqueous Solution of 50% Honda ® LC coolantfor 150 hours at 105° C. Compo- Shear Type of sition Strength (psi) %Change¹ Failure  7 45 −71% 95% AF 10 48 −64% 85% AF 12 30 −84% 98% AF 13119   28% 80% AF ¹Change in shear strength from pre-immersionmeasurement (Table 3).

TABLE 5 Lap Shear Measurements for Compositions 7, 10, 12 and 13Subsequent to Immersion in Honda ® MTF Gear Oil for 150 hours at 120° C.Compo- Shear Type of sition Strength (psi) % Change¹ Failure  7  84 −45%90% AF 10 176  32% 100% CF 12 127 −34% 65% AF 13 25 −73% 100% AF ¹Changein shear strength from pre-immersion measurement (Table 3).

As shown in Tables 4 and 5, the specimens were subjected to the extremetest of immersion in these respective fluids for 150 hours at 105° C.This test was an accelerated aging test designed to approximate theextended real life use. In each case, as expected, some tensile strengthwas lost, but sufficient useful bond strength remained and each specimenexhibited some cohesive failure. Shear strength measurements takensubsequent to immersion illustrate that the compositions maintainedacceptable adhesion and cohesion despite extended fluid contact. Basedon automotive industry specifications, these results suggests that theamino-silane containing compositions of the present invention aresuitable sealing and bonding agents for magnesium alloy substrates whenused in automotive applications.

Additional inventive compositions were made using the same procedureused to make the Base Compositions set forth previously. These inventivecompositions are set forth below in Table 6 are labeled Compositions15-30.

TABLE 6 Inventive Compositions 15-30¹. Compo- % Sili- % % Cross-linking% Adhesion sition cones² Fillers³ Silanes⁴ Promoters⁵ 15 47.90 46.904.90 0.30 16 45.20 48.55 5.50 0.75 17 55.20 37.55 6.50 0.75 18 45.2047.55 6.50 0.75 19 47.30 45.65 6.00 1.05 20 47.80 44.70 6.75 0.75 2147.50 44.90 6.75 0.85 22 45.50 47.00 6.75 0.75 23 48.60 44.65 6.00 0.7524 49.00 43.50 6.50 1.00 25 49.00 43.50 6.50 1.00 26 49.00 43.75 6.500.75 27 49.25 43.50 6.50 0.75 28 48.25 43.50 6.50 1.75 29 50.00 42.506.50 1.00 30 48.00 44.50 6.50 1.00 ¹Details of Compositions 15-30 areshown in Table 6a below. ²Selected from 2000 cps, 6000 cps, and 10,000cps hydroxy-terminated polydimethylsiloxanes. ³Selected from Aluminumpigment powder in mineral oil, Silane-treated fumed silica,Stearate-coated calcium carbonate, Carbon black, Hydrophobic fumedsilica, Magnesium oxide, Iron aluminum silicate, Silylated silica, Alkyltin carboxylate, and Amorphous hydrophobic silica. ⁴Selected from tetra(methyl ethyl ketoximino) silane/vinyl tris (methyl ethyl ketoximino)silane 1:1 and vinyl tris (methyl ethyl ketoximino) silane. ⁵Selectedfrom gamma-ureidopropyltrimethoxy silane, 3-aminopropyltrimethoxysilane, N,N′-bis (3-trimethoxy silylpropyl) urea,trimethoxysilylpropyldiethylene triamine, andaminoethyl-3-aminopropyl-methyl dimethylsilane.

TABLE 6a Details of Compositions 15-30. Composition 15 16 17 18 19 20 2122 23 24 25 26 27 28 29 30 w/w w/w w/w w/w w/w w/w w/w w/w w/w w/w w/ww/w w/w w/w w/w w/w Component % % % % % % % % % % % % % % % % 2000 cpsSilanol¹ 12.0 17.0 12.0 5.7 5.5 11.0 11.0 11.0 11.25 10.25 11.0 11.06000 cps Silanol² 39.4 32.2 38.2 33.2 47.3 47.8 41.8 40.0 48.6 38.0 38.038.0 38.0 38.0 39.0 37.0 10,000 cps Silanol³ 8.5 Carbon Black 0.25 .25.25 .25 0.7 0.7 0.7 .25 0.2 0.2 0.2 0.2 0.2 0.2 0.2 Aluminum Flake⁴ 0.9Silane-treated 2.0 Fumed Silica Silylated Silica 4.0 0.2 2.0 Hydrophobic2.0 2.0 2.0 4.0 3.0 3.0 4.0 4.0 Fumed Silica Hydrophobic 3.0 3.0 3.0Amorphous Silica Stearate-coated 44.0 10.0 10.0 10.0 10.0 10.0 10.0 10.010.0 10.0 10.0 10.0 10.0 10.0 10.0 10.0 Calcium Carbonate CalciumCarbonate 15.0 15.0 25.0 25.0 25.0 25.0 25.0 25.0 25.0 25.0 IronAluminum 30.0 30.0 30.0 30.0 3.0 30.0 Silicate Magnesium Oxide 21.0 10.010.0 5.4 4.0 4.0 5.0 5.0 5.0 5.0 5.0 5.0 TOS/VOS⁵ 1.5 1.5 1.5 1.5 0.750.75 0.75 0.75 0.75 1.5 1.5 1.5 1.5 1.5 1.5 1.5 VOS⁶ 3.4 5.0 5.0 5.05.25 6.0 6.0 6.0 5.25 5.0 5.0 5.0 5.0 5.0 5.0 5.0 Uriedo-Silane⁷ 0.750.75 0.75 0.75 0.75 0.75 0.75 0.75 0.75 0.75 Witco Y-11683⁸ 0.3 0.3 0.30.3 0.3 0.3 0.3 0.55 0.3 0.3 0.3 0.3 3-Aminopropyl 0.3 0.3 0.1Trimethoxysilane Alkyl Tin Carboxylate .06 0.1 Aminomethyl-3- 1.0 1.00.75 1.0 1.0 1.0 aminopropyl-methyl- dimethylsilane ¹2000 cpshydroxy-terminated polydimethylsiloxane ²6000 cps hydroxy-terminatedpolydimethylsiloxane ³10,000 cps hydroxy-terminated polydimethylsiloxane⁴Aluminum pigment powder in mineral oil ⁵Tetra(methyl ethylketoximino)silane/vinyl tris(methyl ethyl ketoximino)silane 11 ⁶Vinyltris(methyl ethyl ketoximino)silane ⁷Gamma-ureidopropyltrimethoxy silane⁸Hexafunctional silyl ethane

Physical properties of the above compositions were measured and lapshear specimens were prepared for these compositions according to theprocedure set forth previously. The compositions were extruded at therate indicated. The results of these measurements are set forth Table 7.

TABLE 7 Physical Properties and Lap Shear Measurements for Compositions15-30. Extrusion Rate Hardness Shore Tensile 100% Modulus Al shear Mgshear Composition (g/min) Å Strength (psi) (psi) % Elongation strength(psi) strength (psi) 15 200 58 295 221 196 202 94 16 150 59 504 342 182— 137 17 340 50 371 202 226 175 77 18 131 56 427 263 252 232 126 19 30042 335 150 228 148 74 20 50 48 570 180 358 144 54 21 44 — — — — — 55 22147 — — — — — 80 23 60 53 323 167 293 — 117 24 330 53 341 241 166 — — 25330 48 376 228 217 — 155 26 340 45 272 189 222 — 70 27 22 50 309 233 177— 83 28 2 50 351 277 146 — 186 29 7 48 419 265 195 — 225 30 7 48 473 307167 — 188¹ ¹20% cohesive failure. Indicates excellent adhesion tomagnesium alloy substrate.

While many of the inventive Compositions 15-30 demonstrate improvedmagnesium shear strength, Compositions 28-30 show particularlyexceptional magnesium shear strength. Optimized Composition 30 was seento demonstrate 20% cohesive failure at a magnesium shear strength of 188psi, indicating that this composition exhibits excellent adherence tomagnesium alloy substrates. Particular compositions were selected fromthe group of Compositions 15-30 and were immersed in selected automotivefluids for selected lengths of time and at selected temperatures, in amanner similar to that of Compositions 1-14. Physical properties and lapshear results were measured subsequent to immersion and the changes inthese measurements from those taken pre-immersion were calculated. Itwas found that these compositions demonstrate exceptional resistance toautomotive fluids. The results of these immersions are illustrated inTables 8-13.

TABLE 8 Physical Properties and Lap Shear Measurements for Compositions15-20 and 23-30 Subsequent to Immersion in Honda ® LC Coolant at 105° C.for 150 Hours. Tensile Mg Shear Al Shear Com- Hardness Strength StrengthStrength posi- Shore A/ (psi)/ % Elongation/ (psi)/ (psi)/ tion Change %Change % Change % Change % Change 15 15/−43 182/−38 793/305 —  75/−63 16 0/−59 — — — — 17 27/−23 111/−70 409/81 — — 18 37/−19  62/−85 307/22 — —19 15/−27 170/−49 496/118  59/−20 102/−31 20 30/−18 335/−41 439/23 90/67 210/46 23 24/−29 196/−39 352/20 — — 24  0/−53 — — 44 — 25 12/−36150/60 478/120  30/−81 — 26 26/−19 207/−24 332/50 122/74 — 27 29/−21204/−34 312/76 124/49 — 28 23/−27 165/−53 354/142  41/−78 — 29 23/−25245/−42 447/129  73/−68 — 30 26/−22 266/−44 318/90 108/−43¹ — ¹20%cohesive failure. Indicates excellent adhesion to magnesium alloysubstrate.

TABLE 9 Physical Properties and Lap Shear Measurements for Compositions15-20 and 23-25 Subsequent to Immersion in an Aqueous Solution of 50%DexCool ® at 105° C. for 150 Hours. Tensile Mg Shear Al Shear Com-Hardness Strength Strength Strength posi- Shore A/ (psi)/ % Elongation/(psi)/ (psi)/ tion Change % Change % Change % Change % Change 15 15/−43182/−38 793/305 — — 16 — — 12/−91 — 17  0/−50 — — 22/−71  42/−76 18 0/−56 — — 29/−77  59/−75 19 19/−23 131/−61 546/139 69/−7  71/−52 2028/−20 288/−49 393/10 84/56 166/15 23  0/−53 — — — — 24  0/−53 — — 95/−— 25  0/−48 — — 91/−41 —

TABLE 10 Physical Properties and Lap Shear Measurements for Compositions19-20 and 23-30 Subsequent to Immersion in Honda ® Gear Oil at 120° C.for 150 Hours. Tensile Mg Shear Al Shear Com- Hardness Strength StrengthStrength posi- Shore A/ (psi)/ % Elongation/ (psi)/ (psi)/ tion Change %Change % Change % Change % Change 19 22/−20 303/−10 267/17 102/38 205/3920 25/−23 443/−22 378/6  55/2 269/87 23 23/−30 348/8 258/−12 — — 24 0/−53 — —  95/− — 25 27/−21 400/6 235/8  91/−41 — 26 32/−13 329/21201/−9  14/−80 — 27 34/−16 357/16 151/−15  11/−87 — 28 30/−20 386/10196/34  83/−55 — 29 26/−22 397/−5 251/29  62/−72 — 30 28/−20 395/−16178/7 117/−38¹ — ¹75% cohesive failure. Indicates excellent adhesion tomagnesium alloy substrate.

As seen in Tables 7, 8, and 10, Composition 30 shows excellent adhesionto magnesium alloy substrates. Composition 30 demonstrates 20% cohesivefailure at a magnesium shear strength of 188 psi prior to immersion inautomotive fluids, 20% cohesive failure at a magnesium sheer strength of108 psi subsequent to immersion in Honda(& coolant, and 75% cohesivefailure at a magnesium shear strength of 117 psi subsequent to immersionin Honda® gear oil. As noted previously, this failure within theadhesive as opposed to failure at the bondline interface indicates thatthe adhesion to the magnesium substrate is stronger than the adhesiveper se. Such failure is desirable in the present invention as itindicates enhanced adherence to the magnesium substrate.

TABLE 11 Physical Properties and Lap Shear Measurements for Compositions16-20 and 24-25 Subsequent to Immersion in Texaco ® 2224 Gear Oil at105° C. for 150 Hours. Tensile Mg Shear Al Shear Com- Hardness StrengthStrength Strength posi- Shore A/ (psi)/ % Elongation/ (psi)/ (psi)/ tionChange % Change % Change % Change % Change 16 33/−26 326/−35 243/34264/93 — 17  0/−50 — — — — 18  0/−56 — — — — 19 10/−32  52/−84 669/193131/77 124/−16 20  0/−48 — —  38/−89 120/−17 24  0/−53 — — — — 25  0/−48— — — —

Selected Compositions 15-30 were subjected to addition immersion testsand their physical properties were measured. The changes in physicalproperties from those measured pre-immersion were also calculated. Theseresults are presented in Tables 12-15.

TABLE 12 Physical Properties for Compositions 14-19 After Aging For 3Days at 82° C. and 3Bond ® Subsequent to Immersion in 5W-30 ® at 120° C.for 150 Hours. Tensile Com- Hardness Strength 100% Modulus % Elongationposi- Shore A/ (psi)/ (psi)/ (in.)/ tion % Change % Change % Change %Change 15 34/−41 396/34 183/−17 263/34 16 42/−29 537/7 305/−11 166/−9 1730/−40 334/−10 162/−20 194/−14 18 35/−38 430/1 203/−23 228/−10 19 — — —— 20 — — — — 3Bond ® 39/−32 490/22 259/−2 203/−11

TABLE 13 Physical Properties for Compositions 16, 19-20 After Aging For3 Days at 82° C. and 3Bond ® Subsequent to Immersion in Texaco ® 2224Gear Oil at 120° C. for 150 Hours. Tensile Com- Hardness Strength 100%Modulus % Elongation posi- Shore A/ (psi)/ (psi)/ (in.)/ tion % Change %Change % Change % Change 16 33/−44 326/−35 133/−61 243/34 19 10/−76 52/−84 — 669/193 20  0/−100  0/−100  0/−100  0/−100 3Bond ®  0/−100 0/−100  0/−100  0/−100

TABLE 14 Physical Properties for Composition 15 After Aging For 3 Daysat 82° C. Subsequent to Immersion in Dexron III ATF ® at 120° C. for 150Hours. Tensile Com- Hardness Strength 100% Modulus % Elongation posi-Shore A/ (psi)/ (psi)/ (in.)/ tion % Change % Change % Change % Change15 25/−57 347/914 127/−839 286/737

TABLE 15 Physical properties for Compositions 15-20 After Aging For 3Days at 82° C. and 3Bond ® Subsequent to Immersion in an AqueousSolution of 50% DexCool ® at 105° C. for 150 Hours. Tensile Com-Hardness Strength 100% Modulus % Elongation posi- Shore A/ (psi)/ (psi)/(in.)/ tion % Change % Change % Change % Change 15 15/−74 182/−38 37/−83 793/305 16  0/−100  0/−100  0/−100  0/−100 17 27/−46 111/−70 45/−78 409/81 18 37/−34  62/−85  39/−85 307/22 19 19/−55 131/−61 35/−78 546/139 20 28/−42 288/−49  77/−57 393/10 3Bond ® 46/−19 221/−45147/−44 214/−6

As the above tables 8-15 illustrate, the inventive compositionsgenerally show a loss of some tensile strength subsequent to immersionin automotive fluids for selected lengths of time and at selectedtemperatures chosen to simulate accelerated aging. However, these tablesshow that the inventive compositions generally maintain sufficient bondstrength following immersion. This indicates that these compositionswould be suitable sealing and bonding agents for magnesium-basedsubstrates used in automotive applications.

Lap shear tests were conducted prior to, and subsequent to, immersion inautomotive fluid solids for selected compositions using aluminum, steeland magnesium substrates, as shown in Tables 16-27. As illustrated inthese tables, the compositions of the present invention demonstrateexcellent adherence to all three of these substrates while maintainingexcellent resistance to automotive fluid solvents.

TABLE 16 Lap Shear Measurements for Compositions 15, 17-20 UsingAluminum Specimens. Shear Joint Cohesive Composition Adhesion (psi)Movement (in.) Failure (%) 15 202 0.11 100  17 175 0.9 85 18 232 0.10490 19 148 0.093 90 20 144 0.118 10

TABLE 17 Lap Shear Measurements for Compositions 15, 17-18 aged for 3days at 82° C. Using Aluminum Specimens Subsequent to Immersion in5W-30 ® at 120° C. for 150 Hours. Shear Joint Cohesive Adhesion (psi)/Movement (in.)/ Failure (%) Composition % Change % Change % Change 15300/49 0.137/25  100/0  17 237/35 0.129/−86 100/18 18 305/31 0.141/36 100/11

TABLE 18 Lap Shear Measurements for Composition 15 aged for 3 days at82° C. Using Aluminum Specimens Subsequent to Immersion in ATF ® at 120°C. for 150 Hours. Shear Joint Cohesive Adhesion (psi)/ Movement (in.)/Failure (%) Composition % Change % Change % Change 15 255/26 0.141/2890/−10

TABLE 19 Lap Shear Measurements for Compositions 15, 17-18 aged for 3days at 82° C. Using Aluminum Specimens Subsequent to Immersion in anAqueous Solution of 50% DexCool ® at 120° C. for 150 Hours. Shear JointCohesive Adhesion (psi)/ Movement (in.)/ Failure (%)/ Composition %Change % Change % Change 15 75/−63 0.196/78   5/−95 17 42/−76 0.114/−8725/−71 18 59/−75 0.142/37  10/−89

TABLE 20 Lap Shear Measurements for Compositions 15, 17-18 aged for 3days at 82° C. Using Steel Specimens. Shear Joint Cohesive CompositionAdhesion (psi) Movement (in.) Failure (%) 15 207 0.112 90 17 123 0.061 0 18 189 0.084 30

TABLE 21 Lap Shear Measurements for Compositions 15, 17-18 Aged for 3Days at 82° C. Using Steel Specimens After Immersion in 5W-30 ® at 120°C. for 150 Hours. Shear Joint Cohesive Adhesion (psi)/ Movement (in.)/Failure (%)/ Composition % Change % Change % Change 15  91/−56 0.054/−520/−100 17  49/−60 0.041/−33 0/0   18 112/−41 0.068/−19 0/−100

TABLE 22 Lap Shear Measurements for Composition 15 Aged for 3 days at82° C. Using Steel Specimens Subsequent to Immersion in ATF ® at 120° C.for 150 Hours. Shear Joint Cohesive Adhesion (psi)/ Movement (in.)/Failure (%)/ Composition % Change % Change % Change 15 92/−56 0.062/−450/−100

TABLE 23 Lap Shear Measurements for Compositions 15, 17-18 Aged for 3days at 82° C. Using Steel Specimens Subsequent to Immersion in anAqueous Solution of 50% DexCool ® at 120° C. for 150 Hours. Shear JointCohesive Adhesion (psi)/ Movement (in.)/ Failure (%)/ Composition %Change % Change % Change 15 73/−65 0.208/86 5/−94 17 35/−72 0.112/840/0  18 36/−81  0.1/19 5/−83

TABLE 24 Lap Shear Measurements for Compositions 15-20 Aged for 3 daysat 82° C. and 3Bond ® Using Cast Magnesium Alloy Specimens. Shear JointCohesive Composition Adhesion (psi) Movement (in.) Failure (%) 15 940.032 0 16 137  0.069 50  17 77 0.034 0 18 126  0.053 0 19 74 0.049 0 2054 0.029 0 3Bond ® 91 0.033 0

TABLE 25 Lap Shear Measurements for Compositions 15-16 Aged for 3 daysat 82° C. and 3Bond Using Cast Magnesium Alloy Specimens Immersed in5W-30 ® 120° C. for 150 Hours. Shear Joint Cohesive Adhesion (psi)/Movement (in.)/ Failure (%)/ Composition % Change % Change % Change 15 75/−20 0.045/41  0/0 16 292/113 0.110/59  95/90 3Bond ® 151/66 0.100/203 5/−

TABLE 26 Lap Shear Measurements for Compositions 16-18 Aged for 3 daysat 82° C. and 3Bond Using Cast Magnesium Alloy Specimens Immersed in anAqueous Solution of 50% DexCool ® at 105° C. for 150 Hours. Shear JointCohesive Adhesion (psi)/ Movement (in.)/ Failure (%)/ Composition %Change % Change % Change 16 12/−91 0.045/−35   0/−100 17 22/−710.076/124 0/0 18 29/−77 0.106/100 0/0 3Bond ® 63/−31 0.058/76  5/−

TABLE 27 Lap Shear Measurements for Composition 16 Aged for 3 days at82° C. and 3Bond Using Cast Magnesium Alloy Specimens Immersed inTexaco ® 2224 at 120° C. for 150 Hours. Shear Joint Cohesive Adhesion(psi)/ Movement (in.)/ Failure (%)/ Composition % Change % Change %Change 16 264/93  0.113/64  5/−90 3Bond ®  28/−69 0.085/158 5/− 

What is claimed is:
 1. A method for providing enhanced adhesion tomagnesium-based substrates comprising the stops of: a) providing acomposition comprising: (i) at least one polymerizable siliconecomponent; (ii) at least one amino-containing silane adhesion promoter;and (iii)at least one filler; b) disposing said composition between twosubstrates, at least one of which is magnesium-based; and c) curing saidcomposition to effectuate enhanced adhesion thereof.
 2. The method ofclaim 1, wherein said amino-containing silane adhesion promoter isselected from the group consisting of gamma-urcidopropyltrimethoxysilane, 3-aminopropyl trimethoxysilane, N,N′-bis(3-trimethoxysilylpropyl)urea, gamma-aminopropyltrimethoxysilane,N-(2-aminoethyl)-3-aminopropyltriethoxysilane,N-(2-aminoethyl)-3-aminopropyltrimethoxysilane,trimethoxysilylpropyldiethylene triamine, methyltris-(N-methylbenzamido)silane, methyl tris(cyclohexylamino)silane,aminoethyl-3-aminopropyl-methyl-dimethylsilane, tertiary alkyl carbamatesilane, and combinations thereof.
 3. The method of claim 1, wherein saidamino-containing silane adhesion promoter is present in amounts of about0.1 percent by weight of said composition to about 5.0 percent by weightof said composition.
 4. The method of claim 1, wherein saidpolymerizable silicone compound is a room temperature vulcanizablesilicone.
 5. The method of claim 4, wherein said room temperaturevulcanizable silicone is a hydroxy-terminated polydimethylsiloxane. 6.The method of claim 5, wherein said hydroxy-terminatedpolydimethylsiloxane is present in amounts of about 45.2 percent byweight of said composition to about 55.2 percent by weight of saidcomposition.
 7. The method of claim 1, wherein said polymerizablesilicone compound is a heat curable silicone.
 8. The method of claim 1,wherein said polymerizable silicone compound is an actinic radiationcurable silicone.
 9. The method of claim 1, wherein said filler isselected from the group consisting of carbon black, aluminum flake,silane-treated fumed silica, precipitated silica, calcium carbonate,stearate coated calcium carbonate, iron aluminum silicate, magnesiumoxide, talc, ground quartz, clay, titanium dioxide, iron oxide, ceriumoxide, zinc oxide, barium oxide, and combinations thereof.
 10. Themethod of claim 1, wherein said filler is present in amounts of about37.55 percent by weight of said composition to about 38.55 percent byweight of said composition.
 11. The method of claim 1, furthercomprising a silane cross linking agent comprising tetra(methyl ethylketoximino) silane or vinyl tris(methyl ethyl ketoximino) silane.